Adam, what you are looking for is a "quench" line, not a temper line, it indicates the point at which the quench might have stopped, it is a change in colour of the material, but it can disappear after a blade is polished. It does not need to be a straight line, it can be a graduated area.
I've put a couple of arrows onto one of your pics, these arrows DO NOT indicate where I believe a quench line is, they indicate points that can look similar to the area where a quench line might be, & they are in places where a quench line might be expected to be found.
Then again, it is entirely possible that the maker did not wish to heat treat the blade, many decorative, very expensive, modern custom knives do not get a heat treat also. And for the same reason:- if the blade has been made as a work of art & not for intended use, then why risk damage to the blade by bringing it up to critical & plunging it into a quench?
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